Athletes, celebrities react to Muhammad Ali’s death

Muhammad Ali, legendary boxer and social activist, died Friday. He was 74.

Ali was hospitalized on June 2 to be treated for a respiratory issue.

Ali was not only widely considered to be one of the greatest boxers, but his social activism and colorful personality also made him one of the most popular—and polarizing—athletes of all time.

Ali, who was diagnosed with Parkinson’s disease in 1984, was born Cassius Clay. He joined the Nation of Islam in 1964, shortly after winning his first heavyweight title. Ali was arrested in 1967 for refusing to join the United States military. He appealed his case to the Supreme Court, which overturned his conviction in 1971. Ali would win the heavyweight title two more times before turning into a beloved figure in retirement.

After news of his death, numerous athletes and celebrities paid tribute to Ali on Twitter.